Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois, 60637.
Evolution. 2022 Sep;76(9):2049-2066. doi: 10.1111/evo.14577. Epub 2022 Aug 2.
Models of adaptive radiation were originally developed to explain the early, rapid appearance of distinct modes of life within diversifying clades. Phylogenetic tests of this hypothesis have yielded limited support for temporally declining rates of phenotypic evolution across diverse clades, but the concept of an adaptive landscape that links form to fitness, while also crucial to these models, has received more limited attention. Using methods that assess the temporal accumulation of morphological variation and estimate the topography of the underlying adaptive landscape, I found evidence of an early partitioning of mandibulo-dental morphological variation in Carnivora (Mammalia) that occurs on an adaptive landscape with multiple peaks, consistent with classic ideas about adaptive radiation. Although strong support for this mode of adaptive radiation is present in traits related to diet, its signal is not present in body mass data or for traits related to locomotor behavior and substrate use. These findings suggest that adaptive radiations may occur along some axes of ecomorphological variation without leaving a signal in others and that their dynamics are more complex than simple univariate tests might suggest.
适应辐射模型最初是为了解释多样化进化枝内独特生活方式的早期快速出现而提出的。对这一假说的系统发育检验仅为跨多个进化枝的表型进化率随时间下降提供了有限的支持，但与这些模型同样至关重要的是，将形态与适应性联系起来的适应景观的概念受到的关注则更为有限。利用评估形态变异随时间积累并估计潜在适应景观地形的方法，我发现了食肉目（哺乳纲）中下颌牙齿形态变异的早期分区的证据，这一现象发生在一个具有多个高峰的适应景观上，与关于适应辐射的经典观点一致。虽然与饮食相关的特征中存在对这种适应辐射模式的强烈支持，但在体重数据或与运动行为和基质利用相关的特征中，其信号并不存在。这些发现表明，适应辐射可能沿着某些生态形态变异轴发生，而在其他轴上则没有留下信号，其动态比简单的单变量检验所暗示的要复杂得多。
